Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Evidence is presented for the existence of many different systems of proteolytic enzymes in human skeletal muscle. These include the lysosomal system of cathepsins as well as proteinases and peptide hydrolases that are optimally active at neutral and alkaline pH ranges. The majority of proteolytic enzymes examined are found to show increased activity in dystrophic human muscle. Moreover, a high initial rise is observed in cathepsin B1, a thiol-dependent endopeptidase of lysosomes, and in dipeptidyl peptidase IV, a membrane-associated peptidase. In addition, a calcium-activated neutral proteinase is found to be significantly elevated in muscle from patients with Duchenne dystrophy. The possible roles of these proteinases in intracellular protein catabolism and muscle wasting are discussed.
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PMID:Muscular dystrophy and activation of proteinases. 3 47

The proteins of microvilli prepared from pig kidney were analysed by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. The typical pattern stained for protein revealed five major bands, four of which also stained for carbohydrate, and about 15 minor bands. For descriptive purposes the bands were designated numerically by their apparent molecular weights (X10(-3). Well-characterized proteins were identified with four of the five major bands. Dipeptidyl peptidase IV, a serine proteinase that may be specifically labelled with di-isopropyl [32P]phosphorofluoridate, was assigned to band 130. Aminopeptidase M was assigned to band 160, though when released from the membrane by a proteinase, this protein comprises three polypeptides each of lower apparent molecular weight than the native enzyme. Neutral endopeptidase can be assigned to band 95 and actin to band 42. The fifth major band (180) is an extrinsic glycoprotein that has not been identified with any microvillus enzyme activity. These four proteins contribute 21% of the microvillus-membrane protein. Kidney microvillus actin was characterized by a variety of properties and was similar to muscle actin. A computer analysis of the gel pattern indicates that it comprises 9.0% of the microvillus protein. Myosin is not present in the microvillus, but another protein associated with band 95, with properties that distinguish it from neutral endopeptidase, was tentatively identified as alpha-actinin. Alkaline phosphatase was identified as a monomeric polypeptide with an apparent molecular weight of 80000; it is a minor protein of the microvillus and is not discernible as a discrete band in the gel pattern. These and other results permit a model of the organization of the microvillus protein to be suggested. The computer program used has been deposited as Supplementary Publication SUP 50070 (12 pages) at the British Library Lending Division, Boston Spa. Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms given in Biochem. J. (1976) 153,5.
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PMID:Proteins of the kidney microvillus membrane. Identification of subunits after sodium dodecylsullphate/polyacrylamide-gel electrophoresis. 13 63

Among the five peptidase known to be located in the microvillus membrane of the renal proximal tubule are two enzymes with endopeptidase activity. Neutral endopeptidase, a zinc-dependent enzyme, has a broad specificity comparable to that of thermolysin, and like the latter may be specifically inhibited by phosphoramidon. Dipeptidyl peptidase IV, a serine enzyme, is very sensitive to inhibition by diisopropyl phosphorofluoridate. It is also capable of endopeptidase activity, hydrolysing bonds involving the carboxyl group of proline.
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PMID:Endopeptidases in the brush border of the kidney proximal tubule. 24 85

The membrane of kidney microvilli is richly endowed with peptidases. Present information is that there are at least eight examples located in this membrane. Three of the group are known to be among the major proteins that can be identified by dodecyl sulphate electrophoresis of the purified microvillus fraction. These three peptidases, aminopeptidase M, serine peptidase (dipeptidyl peptidase IV) and neutral endopeptidase can be labelled by lactoperoxidase iodination from either the luminal or the inner surfaces of the membrane, a result consistent with the view that the polypeptide chains span the microvillus membrane. The serine peptidase has been purified by two methods, permitting a comparison of the detergent-released and proteinase-released forms. The two forms differ in the presence and absence of the hydrophobic anchor that secures the enzyme to the membrane. Preliminary studies support the view that this hydrophobic domain is relatively small and that it includes the N-terminal region of the polypeptide chain.
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PMID:Kidney microvillus peptidases--are they transmembrane proteins? 61 79

Dipeptidyl peptidase IV, an enzyme that releases dipeptides from substrates with N-terminal sequences of the forms X-Pro-Y or X-Ala-Y, was purified 300-fold from pig kidney cortex. The kidney is the main source of the enzyme, where it is one of the major microvillus-membrane proteins. Several other tissues contained demonstrable activity against the usual assay substrate glycylproline 2-naphthylamide. In the small intestine this activity was greatly enriched in the microvillus fraction. In all tissues examined, the activity was extremely sensitive to inhibition by di-isopropyl phosphorofluoridate (Dip-F), but relatively resistant to inhibition by phenylmethylsulphonyl fluoride. It is a serine proteinase which may be covalently labelled with [32P]Dip-F, and is the only enzyme of this class in the microvillus membrane. The apparent subunit mol.wt. estimated by sodium dodecyl-sulphate/polyacrylamide-gel electrophoresis and by titration with [32P]Dip-F was 130 000. Gel-filtration and sedimentation-equilibrium methods gave values in the region of 280 000, which is consistent with a dimeric structure, a conclusion supported by electron micrographs of the purified enzyme. Among other well-characterized serine proteinases, this enzyme is unique in its membrane location and its large subunit size. Investigation of the mode of attack of the peptidase on oligopeptides revealed that it could hydrolyse certain N-blocked peptides, e.g. Z-Gly-Pro-Leu-Gly-Pro. In this respect it is acting as an endopeptidase and as such may merit reclassification and renaming as microvillus-membrane serine peptidase.
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PMID:Dipeptidyl peptidase IV, a kidney brush-border serine peptidase. 96 53

The expression of cell-surface peptidases was examined in two human colon carcinoma cell lines, Caco-2 and HT-29. Enzymic assays revealed the presence of eight cell-surface peptidases on a Caco-2 cell line (passage number 82-88), namely aminopeptidase N, dipeptidyl peptidase IV, peptidyl dipeptidase A (angiotension-converting enzyme), aminopeptidase P, aminopeptidase W, endopeptidase-24.11, gamma-glutamyl transpeptidase and membrane dipeptidase. The presence of dipeptidyl peptidase IV and endopeptidase-24.11 was also confirmed immunochemically. After 15 days culture, the activities of aminopeptidase P, peptidyl dipeptidase A and alkaline phosphatase activities on Caco-2 cells reached a plateau, and that of membrane dipeptidase began to decline. In contrast, aminopeptidase N, dipeptidyl peptidase IV and endopeptidase-24.11 activities were still rising after 26 days in culture. Caco-2 cells of passage number 181-183 were found to lack endopeptidase-24.11, but maintained dipeptidyl peptidase IV expression. Two populations of HT-29 cells were surveyed. Both the standard, undifferentiated population and a differentiated population expressed only three peptidases: dipeptidyl peptidase IV, aminopeptidase W and carboxypeptidase M. In the differentiated HT-29 cells the activity of dipeptidyl peptidase IV after 14-21 days was beginning to plateau whereas aminopeptidase W activity was still rising and that of carboxypeptidase M had begun to decline. These differences in activity profiles observed among this group of cell-surface peptidases indicate that these cell lines, especially Caco-2, are useful models to study the regulation of their expression.
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PMID:A survey of membrane peptidases in two human colonic cell lines, Caco-2 and HT-29. 131 37

Surface peptidase activities on the human monocytic lineage cell line U937 were characterized. Two diisopropyl phosphofluoridate (DFP)-inhibitable serine peptidases were identified by differences in their hydrolytic activities on chromogenic peptides: one removed tripeptides from the free NH2-terminal end of the synthetic peptide Ala-Ala-Phe-p-nitroanilide (pNA) and was not inhibited by inhibitors of metallo-, cysteic-, and aspartic-proteinases, or by those of elastase-, trypsin- and chymotrypsin-like enzymes, suggesting the presence of a hitherto unidentified serine tripeptidyl endopeptidase; the other peptidase catalyzed the release of Gly-Pro from Gly-Pro-pNA and was inhibited by DFP, phenylmethyl sulfonyl fluoride and diprotin A, thus resembling dipeptidyl peptidase IV (DPP IV) with respect to its substrate specificity and inhibitor profile. A group of N-exo-aminopeptidase activities specifically inhibited by bestatin, was also detected when Ala-, Leu-, Arg- and Lys-pNA were used a substrates. The activities were surface associated and not secreted as determined by extracellular location of product and enzymatic recovery in highly purified U937 cell membranes. Peripheral monocytes and macrophages were found to virtually exhibit identical levels of these two classes of peptidase activities when compared to those detected on U937 cells. The relative contributions of these hydrolytic enzymes to the cleavage of bioactive and radioiodinated cytokines including tumor necrosis factor-alpha (TNF-alpha), interleukin-1 alpha and interferon-gamma was next examined. The results indicated that N-aminopeptidases do not appear to participate in the catabolism of any tested cytokine. In contrast, the most interesting finding was that both serine peptidases participate in TNF-alpha degradation. Analysis of the final proteolytic digestion products demonstrated the disappearance of the native 17-kDa molecule TNF-alpha, and the concomitant release of biologically inactive fragments of less than or equal to 2 kDa. Together, these observations indicate new roles for both the DPP IV-like enzyme and the tripeptidyl endopeptidase located at the surface of human monocytic cells, including the regulation of the extracellular TNF-alpha concentration. Thus, the identification of functional ectopeptidases provides insight into their potential role in both normal and malignant monocytic function.
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PMID:Human U937 cell surface peptidase activities: characterization and degradative effect on tumor necrosis factor-alpha. 134 32

The human colon cancer cell line Caco-2 undergoes spontaneous enterocytic differentiation during growth, and expresses a number of brush-border-membrane-associated hydrolases typical of a differentiated phenotype. Among these are alkaline phosphatase, dipeptidyl peptidase IV and sucrase-isomaltase (sucrase, EC 3.2.1.48). Neutral endopeptidase 24.11 [EC 3.4.24.11, neprilysin (NEP)] is another abundant protease of normal enterocytes but its presence in Caco-2 cells has not been fully documented yet. In this paper, we show that Caco-2 cell extracts hydrolyse tritiated [D-Ala2Leu5]enkephalin with a Km of 180 microM, very close to the value obtained for the NEP present in the rabbit kidney (118 microM). Western-blot analysis of brush-border membranes purified from post-confluent cells revealed a protein with an apparent molecular mass of 94000 Da similar to that of the rabbit kidney NEP. The amount of enzyme in cell extracts increased as a function of the age of the culture, indicating that NEP expression is correlated with the degree of cell differentiation as is also the case for sucrase and dipeptidylpeptidase IV (DPP-IV). Binding of a radiolabelled antibody to Caco-2 cell monolayers grown on semi-permeable filters indicated that 95% of NEP molecules present at the cell surface are on the apical side. Immunocytochemical and flow cytometric analysis of intact and permeabilized cells were also used to investigate the presence of NEP and DPP-IV at the surface of Caco-2 cells. Whereas DPP-IV staining appeared to be homogeneous throughout the entire cell population, NEP-related fluorescence exhibited a bimodal distribution which indicates an uneven expression of the protein at the cell surface. Permeabilization of monolayers with saponin before staining restored a labelling pattern for NEP similar to the one obtained for DPP-IV. This suggests that although DPP-IV and NEP follow similar patterns of expression when enzymic activities are measured on whole-cell extracts, targeting of these brush-border proteins to the cell surface appears to be regulated in different ways.
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PMID:Polarized distribution of neutral endopeptidase 24.11 at the cell surface of cultured human intestinal epithelial Caco-2 cells. 136 26

The content of membrane peptidases has been compared in the human astrocytoma clone D384 and the human neuroblastoma line SH-SY5Y. Endopeptidase-24.11 (neutral endopeptidase, EC 3.4.24.11) was detectable only on the astrocytoma cells whereas angiotensin-converting enzyme (EC 3.4.15.1) was selectively expressed on the neuroblastoma line. Dipeptidyl peptidase IV (EC 3.4.14.5) was also abundant on the astrocytoma line. The presence of both endopeptidase-24.11 and dipeptidyl peptidase IV on D384 cells was confirmed by immunohistochemistry. A membrane preparation from D384 cells hydrolyzed both atrial natriuretic peptide and brain natriuretic peptide and, in both cases, the pattern of metabolism was similar to that seen with purified endopeptidase-24.11. The endopeptidase-24.11 inhibitor, phosphoramidon, at 1 microM abolished natriuretic peptide metabolism. The neuroblastoma line, which lacked endopeptidase-24.11, failed to metabolise atrial natriuretic peptide and brain natriuretic peptide, emphasizing the key role of the endopeptidase in hydrolyzing these regulatory peptides at the cell surface.
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PMID:Hydrolysis of atrial and brain natriuretic peptides by the human astrocytoma clone D384 and the neuroblastoma line SH-SY5Y. 168 34

Immunohistochemical techniques have been used to study a group of membrane peptidases in the distal segment of the ulnar nerve of piglets 7 and 14 days after surgical section. Five peptidases were studied, all of which have a wide distribution on the surfaces of many cell types and have roles in metabolising neuropeptides. In normal pig nerves, endopeptidase-24.11 is expressed by both myelin- and nonmyelin-forming Schwann cells. Peptidyl dipeptidase A (angiotensin converting enzyme), aminopeptidase-N and dipeptidyl peptidase IV are present in the microvessels, and aminopeptidase-N is also seen in the perineurial connective tissue. Of this group of peptidases, only aminopeptidase-W is a neuronal marker in normal nerve. Macrophages were identified by two antibodies, 74-22-15 and 40D (which recognises Ia). Short-term cultures of macrophages obtained by alveolar lavage were positively stained by both antibodies and about half of the cells also expressed aminopeptidase-N and dipeptidyl peptidase IV. Staining by 40D and 74-22-15 revealed the presence of significant numbers of macrophages in normal nerve, but none of the membrane peptidases colocalized with these cells. Seven days after section of the nerve, the distal segment showed morphological changes typical of Wallerian degeneration. Endopeptidase-24.11 was no longer visible in myelin sheaths, but remained a marker for the surface of Schwann cells (defined also by staining for glial fibrillary acidic protein). The macrophage markers revealed marked changes in the morphology of these cells, often consistent with their phagocytic activity. Two peptidases, aminopeptidase-N and aminopeptidase-W, also appeared at this time to be associated with cells exhibiting the morphology of activated macrophages. This association could be confirmed in many instances by double staining with 74-22-15 and antibodies to the peptidases. Angiotensin converting enzyme retained its single location in microvessels at 7 days after section, but at 14 days a new pattern emerged as it, too, was expressed by macrophages. Dipeptidyl peptidase IV was not shown to be a macrophage marker in the degenerating nerve. Thus Wallerian degeneration leads to remarkable changes in the cellular expression of membrane peptidase; endopeptidase-24.11 reflects the changed morphology of Schwann cells while aminopeptidase-N, aminopeptidase-W and angiotensin converting enzyme become expressed by the actively phagocytosing macrophages.
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PMID:Cellular reorganisation of membrane peptidases in Wallerian degeneration of pig peripheral nerve. 168 7


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